The invention relates to the production and assembly of engines, and relates in particular to systems and methods for assembling rotors in gas turbine engines.
A configuration of the modules of a typical gas turbine engine include a low pressure compressor 10, a high pressure compressor 12, a high pressure turbine 14, and a low pressure turbine 16. During operation of the engine system of the invention as shown in FIG. 1. During operation, air flows into the low pressure compressor 10, then to the high pressure compressor 12, through the high pressure turbine 14, and lastly through the low pressure turbine 16. A first shaft 18 connects the low pressure compressor 12 to the low pressure turbine 16, and a second concentric shaft 20 of larger diameter connects the high pressure compressor 14 to the high pressure turbine 14. The shaft 20 spins faster (in revolutions per minute) than the smaller diameter shaft 18. The blades that are inserted on the respective rotors vary in size. The blades on the rotors of the faster shaft 20 are smaller and produce less thrust than the blades on the rotors of the slower shaft 18. The spacing between the concentric shafts 18 and 20 is maintained with bearings and journals.
As shown in FIG. 2, a typical conventional procedure for assembling each module of an engine begins (step 200) by providing the rotatable parts for assembly (step 202). The rotatable parts are then measured using a conventional measuring system, such as Coordinate Measuring Machine, or CMM (step 204). From the measurements of the parts, the angle of maximum runout, or the maximum unbalance point, of each part is used to orient the component parts in a rotor assembly stacking, and a runout table is consulted to identify the largest deviation from flatness of each component part (step 206). When the components are stacked, the points of maximum unbalance, runout or flatness deviation, are alternately offset by 90 or 180 degrees in an attempt to build a straight rotor (step 208). Runout measurements are then taken with a dial indicator of an assembled stack on tooling supplied by an engine manufacturer (step 210). If the runout is not within tolerance (step 212), then the rotor is disassembled (step 214), and the problem is diagnosed (step 216). A revised plan is then developed to build the rotor (step 218) and the system returns to step 210. If the runout is within tolerance (step 212), then the rotor is placed in an engine, and the engine is moved to a test cell where its performance is tested (step 220). If the engine performance meets the defined criteria, then the system ends (step 222). If the engine performance does not meet the defined criteria, then the system returns to step 216 and diagnoses the problem.
This iterative process may require several days or weeks to build the modules of an engine that meets the specified deviation and an engine that meets the specified performance tolerances.
There is a need for a system and method for assembling rotors in a turbine engine that more efficiently and economically achieves an engine that meets any specified deviation and performance tolerances.